BUG #14498: Default role should be case sensitive when created in Windows

The following bug has been logged on the website:

Bug reference: 14498
Logged by: L Ryan
Email address: liomry(at)gmail(dot)com
PostgreSQL version: 9.6.1
Operating system: Windows 7
Description:

My windows username is "L", I'm new to PostgreSQL and was setting up for
ruby on rails using Webstorm.

Even when I created a "ruby" role with database and used -U for the command
line tools a lot of the Webstorm tools defaulted to using 'L' as they did
not set the -U switch.

I think it would be very helpful to automatically wrap the default role in
"" when creating it in the installer as Unix usernames will be lowercase
anyway and Windows users won't waste hours trying to troubleshoot various
tools which keep saying that the "L" role does not exist.

It seems like this is a very small change that will help prevent frustration
for new users trying out PostgreSQL